CHAPTER III. 



FORMATION OF CORAL REEFS AND ISLANDS, AND 

 CAUSES OF THEIR FEATURES. 



I. FORMATION OF REEFS. 



I. ORIGIN OF CORAL SANDS AND THE REEF-ROCK. 



Very erroneous ideas prevail respecting the appearance of a 

 bed or area of growing corals. The submerged reef is often 

 thought of as an extended mass of coral, alive uniformly over 

 its upper surface, and as gradually enlarging upward through 

 this living growth ; and such preconceived views, when ascer- 

 tained to be erroneous by observation, have sometimes led to 

 skepticism with regard to the zoophytic origin of the reef-rock. 

 Nothing is wider from the truth : and this must have been 

 inferred from the descriptions already given. Another glance 

 at the coral plantation should be taken by the reader, before 

 proceeding with the explanations wdiich follow. 



Coral plantation and coral field are more appropriate appel- 

 lations than coral garden, and convey a juster impression of 

 the surface of a growing reef. Like a spot of wild land, 

 covered in some parts, even over acres, with varied shrubbery, 

 in other parts bearing only occasional tufts of vegetation in 

 barren plains of sand, here a clump of saplings, and there a 

 carpet of variously-coloured flowers in these barren fields — 

 such is the coral plantation. Numerous kinds of zoophytes 



